Studs vs Bolts/Setscrews

[Ed Straker]

Having sheared a driving member bolt which has broken off into the hub I have been wondering if there is a better solution for  this and in also in general.

Would making up a suitable set of BSW studs which are then installed into the hubs to allow the driving members to be held by nuts/washers etc be a good or bad idea?

(My water pump is held on using studs threaded into the block)

Regards

Jamie

[diffwhine]

I'm not sure if it would make that much of a difference. Usually the bolts sheer off as a result of some previous overtightening and damaging the bolt structure. I would run with new quality bolts and that should be more than enough. Some Toyota Land Cruisers use studs there, but I'm not sure if I can sufficent advantage. Also if you impact on the end of one of the threads, it will be a job to get the nut off again without stripping it or the thread.

[Craig T]

They are BSF threads.

The proper bolts are hardened ones I assume so making soft steel studs that you can cut a thread onto is probably a downgrade.

How did you break one off, through normal driving or when tightening / undoing them? If it was through driving I would expect them all to shear off, not just one?

Craig.

[GHOBHW]

I had an issue with these on my 130 years ago.

kept snapping the bolts into the hub from the flange, just one at a time usually, caused by the backlash from the rear axle, very annoying.

was a salisbury so ended up just buying another complete low mile axle and it solved the issue

[Bradley66]

They are BSF threads.

The proper bolts are hardened ones I assume so making soft steel studs that you can cut a thread onto is probably a downgrade.

How did you break one off, through normal driving or when tightening / undoing them? If it was through driving I would expect them all to shear off, not just one?

Craig.

Unlikely they would be hardened in any way. The bolt needs to be of a suitable grade to fail first otherwise you would stripping threads in the hub.
3/8 BSF x 1.600" long according to my parts list.

[diffwhine]

I had an issue with these on my 130 years ago.

kept snapping the bolts into the hub from the flange, just one at a time usually, caused by the backlash from the rear axle, very annoying.

was a salisbury so ended up just buying another complete low mile axle and it solved the issue

That was a common ongoing issue. On Defenders, the official line is that those bolts are replaced each time they are removed. They come with a locking compound on the threads.

[Craig T]

They are definitely high tensile bolts. I have a bunch lying on the desk at home at the minute.. I'll see what tensile strength letter is marked on the head later.

Craig.

[autorover1]

Presumably if tightened correctly the bolts are in tension, but not is shear as the friction between the hub and flange should take all the torque

[TimV]

They are being tightened to the correct torque? 30-38lbft?

[biloxi]

And that may very well be the problem. My books show 28 lb ft
.W..

[diffwhine]

Its one that opens debate... The S3 manual states 30 - 38 lb ft. The 2/2A Manual states 28 lb ft... Same bolts, same hubs... 

Presumably it was deemed necessary to make them tighter?

[biloxi]

These are used drive flange bolts p/n 215331 3/8 BSF X 1-19/32"long. Most of them show signs of deformity to some degree,
caused by  over tightening. Best detected by running your fingers over the thread where it meets the shank.
.W.

[w3526602]

Hi,

There used to be a firm manufacturing high tensile socket head screws (tightened with an ALLEN key) that were warranted not to break. I think they were called UNBRAKO.

There was another firm manufacturing a thread recovery device, but I can't remember their name. It required the damaged thread to be drilled out, and re-tapped with a special tap, after a special insert (looking like a coil spring) had to be screwed into that tapped hole, after which , a new stud, or bolt, could be screwed into the female element of the "spring".

Aside comments ... A spring washer provides a small gap through which water can seep. A tight fastener will only "pull" on one side of the thread, leaving a minute gap on the other side of the thread, through which water can seep. Perhaps immersible items should be fastened with with bolts, and plain washers, so there are no minute gaps to invite the wet stuff in. Is LOCTITE water and shake proof?

A proper engineer would cross-drill the bolt heads, and use locking wire.

Many yonks ago (during my teens), I got involved in removing the bell frame from Addington (near Croydon) Parish Church. My firm , Gillett & Johnson, were suppling a set of new bells. After dropping the (5cwt?) bells down to ground level, (60ft below) using a long chain hoist (aka block & tackle), we had to dismantle the bell frame ... 6" 6" timber, presumably oak, that sat up there for over a hundred years, and was held together by long 1/2" diameter coach screws (wood screws with hexagon heads). It quickly became that there were two blokes built the frame ... some screws came out looking like new ... the others were absolute "pigs". I assume one bloke had greased his screws, but the hadn't.

Me? I usually smear my threads with grease during assembly. Maybe water-pump grease would be preferable?

Regarding EARLY S2 wheel hubs, which used double ended studs. Rovers screwed the studs into the hubs, then peened the end over to prevent then being unscrewed. This was OK, until the nut became reluctant to undo, which resulted in the stud screwing out of the hub, with the peening wreaking havoc with the threads in the hub. Even worse. I have often met studs where a PO has tried to prevent the stub from turning, with a blob of weld, which really "goes to town" on the threaded holes in the hub.

S2A hubs used splined studs, which I presume are "pressed" into the hub, at the factory.

I have drilled out many mangled threads with a 9/16" dia drill in my Dead & Blacker, and used a new "sacrificial" nut, with lots of grease, to pull the splined stub into place. Not having "facities", this was done when "working in the gutter". Not good engineering practice, but they never came back to bite me ... definitely better than listening to the "creaking" due to only two adjacent nuts holding the wheel on.

The idea solution would be to fit S3 hubs, with their 16mm splined studs. That will cost you a new "one and one sixteenth" socket, and "something" over £20 for 20 new wheel nuts. The last time I looked (some years ago),new S3 hubs, complete with bearing and studs ... I can't remember if nuts were included ... were close on £120 per corner. I hope that scrutineers would not penalise a Landy for having bigger nuts? Surely they would improve safety?

602

[Bradley66]

Its one that opens debate... The S3 manual states 30 - 38 lb ft. The 2/2A Manual states 28 lb ft... Same bolts, same hubs... 

Presumably it was deemed necessary to make them tighter?

A quick fag packet Calc gives a maximum torque value of just over 50lb ft for an appropriate bolt material , which fits in with 38ftlb . Thats a dry torque value , people will insist on applying oil or grease to bolts. Hence the stretched and sheared bolts.

[agg221]

Slightly late to the discussion here but:

Bolts threaded into parts mean that the thread in the part wears every time the bolt is fitted/removed.
Studs threaded into parts means the primary wear is where the nut is fitted/removed. When the nut wears out/rounds off/corrodes too much it is relatively small, cheap and easy to replace. Only when the thread on the stud finally wears does the stud itself need to be removed and replaced so the threaded holes in the component itself wear at a far lower rate, preserving the most expensive part and hugely extending its life so is a much better way of doing it from an engineering perspective.

But

If you can slide the part straight over the studs the above applies. If you need to drop the part out sideways then this can only be done with bolts.

Nuts and bolts through flanges is the ideal arrangement.

If you want to go a step further then you use higher wear resistant studs than the nuts, so you might use EN8 studs with EN1A nuts for example. Pre-war sized BSF nuts were taller than the post-war standard which allowed for them being made from a lower strength material.

Although this all looks quite theoretical, you can see where it has been applied by design engineers on higher quality engineered products and when the assembly is designed for repair.

Alec